Arbitration — Jurisdiction — ICSID arbitration clauses in agreements between government and company — Whether superseded by later agreement — Jurisdiction ratione materiae — Doctrine of forum prorogatum — Written submissions — Whether sufficient evidence of acceptance of tribunals’ jurisdiction

Arbitration — Annulment — Grounds for annulment — Excess of jurisdiction — Requirement that excess must be manifest — Uncertainty to be resolved in favorem validitatis sententiae — Distinction between non-application of applicable law and mistaken application of applicable law — Alleged absence of deliberation and other irregularities — Alleged lack of impartiality — Whether constituting failure of tribunal to adhere to fundamental rules of procedure — Contradiction of reasons — Dubious or hypothetical reasons — Sufficiently relevant reasons — Alleged failure of tribunal to deal with questions submitted to it — Challenge to award of arbitral tribunal — ICSID — Reference to ad hoc Committee — Powers of Committee — Whether limited to annulment for manifest excess of jurisdiction — Whether error of law constituting manifest excess of jurisdiction — Consequences of annulment — Whether award to be annulled in whole or in part

Arbitration — Applicable law — ICSID arbitration — Absence of express choice of law — Law of Contracting State to apply — Inclusion of Contracting State’s rules on conflict of laws — Part of Contracting State applying common law while other part applying civil law — Geographical location of project — Applicability of civil law

Claims — For breach of contract — Effect of non-disclosure of circumstances adversely affecting profitability of project — Deductions from claim as result of failure adequately to perform contractual obligations — Exceptio non adimpleti contractus — Release of one party from obligations by virtue of non-performance by other party — Whether principle of international law

Claims — Counterclaim — For damages — Claim by State for losses attributable to participation in failed joint venture project — Capital contribution to joint venture company — Government-guaranteed loans — Non-financial damages — Alleged failure of company to perform duty of disclosure — Effect of denial of company’s claim for contract price on government’s counterclaim

Treaties — Interpretation — Annulment provisions of ICSID Convention — Interpretation of provisions relating to applicable law — Whether interpreted in accordance with general principles of treaty interpretation